svelte:component for dynamic components - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to render a dynamic component using svelte:component.

Svelte

<script>
  import Button from './Button.svelte';
  let current = [1];
</script>

<svelte:component this={current} />

Drag options to blanks, or click blank then click option'

Abutton

BButton

CComponent

Dcurrent

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string like 'Button' instead of the imported component variable.

Using lowercase 'button' which is an HTML tag, not a Svelte component.

You assign the imported component Button to the variable current. Then svelte:component uses this={current} to render it dynamically.

2fill in blank

medium

Complete the code to switch the dynamic component based on a condition.

Svelte

<script>
  import A from './A.svelte';
  import B from './B.svelte';
  let useA = true;
  let current = useA ? [1] : B;
</script>

<svelte:component this={current} />

Drag options to blanks, or click blank then click option'

AA

BB

CuseA

Dcurrent

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string 'A' instead of the imported component variable.

Using the variable useA instead of the component.

The ternary operator chooses A if useA is true, otherwise B. So current must be assigned A or B.

3fill in blank

hard

Fix the error in the code to correctly pass props to the dynamic component.

Svelte

<script>
  import Card from './Card.svelte';
  let current = Card;
  let title = 'Hello';
</script>

<svelte:component this={current} [1] />

Drag options to blanks, or click blank then click option'

Atitle

Btitle:title

Ctitle={title}

Dtitle=>title

Attempts:

3 left

💡 Hint

Common Mistakes

Passing props without curly braces, which treats them as strings.

Using incorrect syntax like title:title.

Props are passed like HTML attributes in Svelte. Use title={title} to pass the variable title as a prop.

4fill in blank

hard

Fill both blanks to render a dynamic component with a fallback if the component is null.

Svelte

<script>
  import X from './X.svelte';
  let current = [1];
</script>

{#if current}
  <svelte:component this={current} />
[2]
{/if}

Drag options to blanks, or click blank then click option'

AX

B<p>No component selected</p>

C<p>Loading...</p>

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning null to current without fallback.

Using fallback text outside the {#if} block.

Assign X to current. Use an {#if} block to check if current exists. If not, show fallback text like <p>No component selected</p>.

5fill in blank

hard

Fill all three blanks to create a dynamic component that updates on button click.

Svelte

<script>
  import One from './One.svelte';
  import Two from './Two.svelte';
  let current = [1];
  function toggle() {
    current = current === One ? [2] : One;
  }
</script>

<button on:click=[3]>Toggle</button>
<svelte:component this={current} />

Drag options to blanks, or click blank then click option'

AOne

BTwo

Ctoggle

Dtoggle()

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function immediately with toggle() instead of passing the function reference.

Using strings instead of component variables.

Start with current = One. The toggle function switches between One and Two. The button's click event uses on:click={toggle} to call the function.

Practice

1. What does the svelte:component tag do in Svelte?

easy

A. It imports components from external libraries.

B. It creates a new Svelte component file.

C. It renders a component dynamically based on a variable.

D. It styles components with CSS.

Solution

1. Step 1: Understand the purpose of svelte:component

   This tag is used to render different components dynamically depending on a variable's value.

2. Step 2: Compare with other options

   Creating files, styling, or importing are unrelated to svelte:component.

3. Final Answer:

   It renders a component dynamically based on a variable. -> Option C

4. Quick Check:

   svelte:component = dynamic rendering [OK]

Hint: Remember: svelte:component means dynamic component rendering [OK]

Common Mistakes:

• Thinking it creates new component files
• Confusing it with CSS styling
• Assuming it imports components

2. Which of the following is the correct syntax to render a dynamic component stored in variable CurrentComp?

easy

A. <component this={CurrentComp} />

B. <svelte:component this={CurrentComp} />

C. <svelte:component src={CurrentComp} />

D. <Component this={CurrentComp} />

Solution

1. Step 1: Recall correct tag and attribute

   The correct tag is svelte:component and the attribute to specify the component is this.

2. Step 2: Check each option

   <svelte:component this={CurrentComp} /> uses correct tag and attribute syntax. Others use wrong tags or attributes.

3. Final Answer:

   <svelte:component this={CurrentComp} /> -> Option B

4. Quick Check:

   Correct tag and this attribute = <svelte:component this={CurrentComp} /> [OK]

Hint: Use svelte:component this={variable} for dynamic components [OK]

Common Mistakes:

• Using component instead of svelte:component
• Using src instead of this
• Capitalizing tags incorrectly

3. Given the code:

  <script>
    import A from './A.svelte';
    import B from './B.svelte';
    let comp = A;
  </script>

  <svelte:component this={comp} />

  <button on:click={() => comp = B}>Switch</button>

What happens when the button is clicked?

medium

A. The displayed component switches from A to B.

B. Nothing changes because comp is not reactive.

C. An error occurs because components cannot be switched dynamically.

D. Both components A and B render at the same time.

Solution

1. Step 1: Understand the initial rendering

   The variable comp starts as component A, so A renders initially.

2. Step 2: Analyze the button click

   Clicking the button sets comp to B, which triggers Svelte to render component B dynamically.

3. Final Answer:

   The displayed component switches from A to B. -> Option A

4. Quick Check:

   Dynamic this changes component = The displayed component switches from A to B. [OK]

Hint: Changing this variable updates the rendered component [OK]

Common Mistakes:

• Thinking dynamic components can't switch
• Assuming comp is not reactive
• Expecting both components to render simultaneously

4. What is wrong with this code snippet?

<script>
  import X from './X.svelte';
  let comp = 'X';
</script>

<svelte:component this={comp} />

medium

A. You cannot use variables inside this.

B. The import statement is incorrect.

C. The svelte:component tag must be self-closing.

D. The variable comp should hold the component, not a string.

Solution

1. Step 1: Check the type of comp

   The variable comp is assigned the string 'X', but it should hold the imported component itself.

2. Step 2: Understand this attribute requirements

   this expects a component reference, not a string name.

3. Final Answer:

   The variable comp should hold the component, not a string. -> Option D

4. Quick Check:

   this needs component, not string [OK]

Hint: Assign component imports, not strings, to this [OK]

Common Mistakes:

• Assigning component name as string
• Thinking svelte:component can't be self-closing
• Believing variables can't be used in this

5. You want to render a dynamic component with props. Given components Cat and Dog both accept a name prop, how do you pass name="Buddy" to the dynamic component stored in petComp?

hard

A. <svelte:component this={petComp} name="Buddy" />

B. <svelte:component this={petComp} {name}="Buddy" />

C. <svelte:component this={petComp} props={{name: 'Buddy'}} />

D. <svelte:component this={petComp} bind:name="Buddy" />

Solution

1. Step 1: Recall how to pass props to components

   Props are passed as attributes directly on the component tag, including svelte:component.

2. Step 2: Check each option's syntax

   <svelte:component this={petComp} name="Buddy" /> correctly passes name="Buddy". <svelte:component this={petComp} {name}="Buddy" /> uses invalid syntax. <svelte:component this={petComp} props={{name: 'Buddy'}} /> tries to pass props as an object, which is not supported. <svelte:component this={petComp} bind:name="Buddy" /> uses bind: incorrectly.

3. Final Answer:

   <svelte:component this={petComp} name="Buddy" /> -> Option A

4. Quick Check:

   Pass props as attributes on svelte:component [OK]

Hint: Pass props like normal attributes on svelte:component [OK]

Common Mistakes:

• Trying to pass props as an object
• Using bind: incorrectly
• Using curly braces around prop name with value